1. Field of the Invention
The present invention relates, generally, to a wheel alignment assembly and method for determining the proper alignment of a vehicle wheel using this assembly. More specifically, the present invention relates to a vehicle wheel support device for use in a wheel alignment assembly.
2. Description of the Related Art
Proper vehicle wheel alignment is an important parameter which is closely monitored during vehicle production in order to provide a smooth, safe ride and to minimize tire wear. Thereafter, vehicle wheel alignment may be periodically checked and adjusted to maintain optimal vehicle operations in the field. Wheel alignment machines are used both during vehicle production and in the field to measure and adjust the toe angle, camber angle, caster angle and ride height of the vehicles. Depending on the sophistication of the machine, other vehicle parameters may be measured and tracked. Historical data and statistical analysis may be recorded and calculated as well.
During vehicle production, the wheels are typically aligned using production alignment machines which are characterized by high vehicle throughput. Any given production facility may employ three or more of these machines. The fully assembled vehicle is driven onto the base of the machine and each tire positioned between a pair of small, parallel rollers by rolling over same. One of the rollers is powered to rotate the wheel during alignment. Conversely, the vehicle tires may contact a large drive roller located between the small parallel rollers which rotates the wheel during the alignment process. The rollers are typically supported on an assembly which is movable to accommodate variances between different vehicles. The roller assembly is also typically movable to compensate for and equalize forces acting on the vehicle wheel which may cause inaccurate alignment readings.
While the roller assembly per se may be movable, the rollers themselves are typically fixed and do not move relative to each other. They also typically remain at all times parallel to each other. However, U.S. Pat. No. 5,513,438 issued to Emmons on May 7, 1996 discloses a wheel support system used in a wheel alignment machine including a pair of rollers which may independently pivot about a pair of axes relative to each other and the base into a non-parallel orientation. The pivotal rollers are fixed against lateral movement relative to each other and otherwise operate in a conventional manner.
Production vehicle wheel alignment machines are also typically characterized in that they require no tooling or fixtures mounted to the tire. They commonly employ electronic measuring devices which measure wheel alignment parameters without physically contacting the vehicle wheel. However, production wheel alignment machines also suffer from the disadvantages that they are complex, structurally intricate and relatively expensive to manufacture and maintain.
In addition to production wheel alignment machines, wheel alignment auditing machines are employed during vehicle production to check the accuracy of the production machines by verifying the alignment of sample vehicles on a statistical basis. In contrast to their production counterparts, wheel alignment auditing machines of the related art are generally characterized by employing tooling or some fixture which is mounted to the vehicle wheel for verifying wheel alignment. While wheel alignment auditing machines are generally less expensive than production machines, they suffer from the disadvantage of being more labor intensive and providing a much lower vehicle throughput than production machines. Wheel alignment devices employed in the field to service vehicles on the road are generally even less expensive but much more labor intensive and slower to operate.
All of the wheel alignment devices employed in the related art have in common the goal of isolating the vehicle wheel from external forces during the alignment process. However, most suffer from an inability to completely equalize all such forces or only achieve this result by employing very expensive mechanisms or slow, labor intensive apparatuses. Thus, there is a need in the art for a wheel alignment assembly which is not overly complex, relatively cost effective, easy to use and efficient and which provides respectable processing times while isolating all forces acting on the vehicle wheel for accurate wheel alignment readings.
The present invention overcomes the disadvantages in the related art in a vehicle wheel support device for use in a wheel alignment assembly. The wheel alignment assembly may include a base on which a vehicle is supported during the measuring operations and a source of structured light for projecting a structured light pattern onto the tire of the vehicle. The assembly also includes a vehicle wheel support device having a floating plate assembly which is movably supported relative to the base upon which the vehicle is positioned. The floating plate assembly includes a pair of rollers disposed in a fixed, non-parallel orientation with respect to each other. The floating plate assembly is movably positionable such that the vehicle wheel may be located between the pair of rollers to isolate the vehicle wheel from the base so as to stabilize all forces acting thereon. Rotational movement is then imparted to the wheel via the rollers so that various wheel alignment parameters may be measured. A method of measuring predetermined alignment characteristics of a vehicle wheel employing the wheel alignment assembly of the present invention is also disclosed.
The fixed, non-parallel orientation of the rollers with respect to each other as well as the non-parallel position of at least one of the rollers relative to the base serves to provide a stabilizing effect on the vehicle wheels after having been lifted from the base and results in an equalization of all forces acting on the vehicle wheel without using fixtures or any other vehicle contacting mechanism. This result is achieved in a vehicle wheel support device which avoids the relative complexity of similar devices employed in the related art. As such, the vehicle wheel support device employed in the wheel alignment assembly of the present invention is also cost effective and easy to use and enjoys respectable vehicle throughput processing times.
One advantage of the wheel alignment assembly of the present invention is that it optimizes wheel alignment audit procedures while eliminating contact with the vehicle body and chassis, shortens cycle time and ensures the accuracy and repeatability of wheel alignment.
Another advantage of the present invention is that it allows for reduced operator influence on measurements, facilitates low maintenance costs and reduced downtime.
Still another advantage of the present invention is that it allows for simple set up and calibration, fast data acquisition and processing.
And still another advantage of the present invention is that it provides for simplified operation, ease of service and provides for on-line troubleshooting.